Renal changes of streptozotocin-induced diabetic rats fed a low-zinc diet

The changes in kidneys of streptozotocin (STZ)-induced diabetic rats fed a low-zinc (LZ) diet were observed. Calcium deposits were detected in the LZ-diabetic groups from the 2nd to the 8th week. The deposits were mainly detected in the corticomedullary junction, and found in the tubular lumina and epithelial cytoplasm and interstitium. Tubular morphological changes, including luminary distension, epithelial flattening, and paleness of cytoplasm and nuclei, were observed near the calcium deposits in the LZ-diabetic group over the 2nd week. Moreover, at the 8th week, wedge-shaped vasogenic lesions were found on the surface of the renal cortex in the LZ-diabetic group. No changes were detected in the control for the LZ or in the diabetic group fed a standard (SC) diet. When STZ was administered, plasma glucose level in groups fed LZ or SC diet increased in the 1st week, and over the 2nd week, glucose level was maintained at more than 400 mg/dL. Glucose level of the LZ-diabetic group did not differ from that of the SC-diabetic group. However, urinary N-acetyl-beta-D-glucosaminidase activity of the LZ-diabetic group at the 8th week was significantly higher than that of the SC-diabetic group. These findings suggested that low-zinc diet hastens renal damages in diabetic rats.